syncthing/lib/tlsutil/tlsutil.go
2015-09-02 21:05:54 +01:00

121 lines
3.1 KiB
Go

// Copyright (C) 2014 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at http://mozilla.org/MPL/2.0/.
package tlsutil
import (
"bufio"
"crypto/rand"
"crypto/rsa"
"crypto/tls"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"fmt"
"io"
"math/big"
mr "math/rand"
"net"
"os"
"time"
)
func NewCertificate(certFile, keyFile, tlsDefaultCommonName string, tlsRSABits int) (tls.Certificate, error) {
priv, err := rsa.GenerateKey(rand.Reader, tlsRSABits)
if err != nil {
return tls.Certificate{}, fmt.Errorf("generate key: %s", err)
}
notBefore := time.Now()
notAfter := time.Date(2049, 12, 31, 23, 59, 59, 0, time.UTC)
template := x509.Certificate{
SerialNumber: new(big.Int).SetInt64(mr.Int63()),
Subject: pkix.Name{
CommonName: tlsDefaultCommonName,
},
NotBefore: notBefore,
NotAfter: notAfter,
KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth, x509.ExtKeyUsageClientAuth},
BasicConstraintsValid: true,
}
derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, &priv.PublicKey, priv)
if err != nil {
return tls.Certificate{}, fmt.Errorf("create cert: %s", err)
}
certOut, err := os.Create(certFile)
if err != nil {
return tls.Certificate{}, fmt.Errorf("save cert: %s", err)
}
err = pem.Encode(certOut, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
if err != nil {
return tls.Certificate{}, fmt.Errorf("save cert: %s", err)
}
err = certOut.Close()
if err != nil {
return tls.Certificate{}, fmt.Errorf("save cert: %s", err)
}
keyOut, err := os.OpenFile(keyFile, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
if err != nil {
return tls.Certificate{}, fmt.Errorf("save key: %s", err)
}
err = pem.Encode(keyOut, &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(priv)})
if err != nil {
return tls.Certificate{}, fmt.Errorf("save key: %s", err)
}
err = keyOut.Close()
if err != nil {
return tls.Certificate{}, fmt.Errorf("save key: %s", err)
}
return tls.LoadX509KeyPair(certFile, keyFile)
}
type DowngradingListener struct {
net.Listener
TLSConfig *tls.Config
}
func (l *DowngradingListener) Accept() (net.Conn, error) {
conn, err := l.Listener.Accept()
if err != nil {
return nil, err
}
br := bufio.NewReader(conn)
conn.SetReadDeadline(time.Now().Add(1 * time.Second))
bs, err := br.Peek(1)
conn.SetReadDeadline(time.Time{})
if err != nil {
// We hit a read error here, but the Accept() call succeeded so we must not return an error.
// We return the connection as is and let whoever tries to use it deal with the error.
return conn, nil
}
wrapper := &WrappedConnection{br, conn}
// 0x16 is the first byte of a TLS handshake
if bs[0] == 0x16 {
return tls.Server(wrapper, l.TLSConfig), nil
}
return wrapper, nil
}
type WrappedConnection struct {
io.Reader
net.Conn
}
func (c *WrappedConnection) Read(b []byte) (n int, err error) {
return c.Reader.Read(b)
}